GENETIC-MAP OF 16 POLYMORPHIC MARKERS FORMING 3 LINKAGE GROUPS ASSIGNED TO RAT CHROMOSOME-4

Sixteen polymorphic markers, including markers for eight new loci, for ming three linkage groups, were assigned to rat Chromosome (Chr) 4 by linkage analysis of the progeny of an F-2 intercross of Fischer (F344/ N) and Lewis (LEW/N) inbred rats. One gene, Igk, was mapped by restric tion fragment length poly morphism (RFLP) analysis. One marker for Tcr b was identified by the polymorphic insertion of a repetitive LINE ele ment. The remaining 14 markers contained polymorphic simple sequence r epeats (SSRs). Ten were identified in genes (Tgfa, Npy, Prss1, Prss2, Aldr1, Iapp, Prp, Eno2, Cacnl1a1, and Il6), one was identified in a se quence related to a gene (Egr4l1), and three were identified in anonym ous DNA segments. The SSR markers were highly polymorphic in 16 inbred rat strains. These markers expand the genetic map of the rat and shou ld be useful in future genetic studies of inbred rats.